The reaction of dihydrocarbylphosphites with a variety of olefinic unsaturated organic compounds, so that a phosphorous-carbon bond is formed, is known in the art, see for background for example: X. Lu and J. Zhu, Synthesis, p. 563-564 (1986); G. Optiz, et. al., Ann., vol. 665, p. 91-101 (1963); I. Tyurenkov, et. al., Khim. Farm. Zh., vol. 22, p. 170-174 (1988); V. Shchepin, et. al., Zh. Obshch. Khim., vol. 57, p. 2144 (1987); and V. Ovchinnikov, et. al., Zh. Obshch. Khim., vol. 54, p. 1916-1917 (1984). None of these disclose the use of vinylpyridines in such reactions.
E. Maruszewska-Wieczorkowska and J. Michalski, J. Org. Chem., vol. 23, p. 1886-1889 (1958) report the synthesis of various 2-(pyridyl)phosphonates by the reaction of a vinylpyridine with a dialkyl phosphite, optionally with a sodium ethoxide catalyst. Without the catalyst, it was reported that yields were lower, and considerable amounts of polymeric substances were formed. Sodium ethoxide, the catalyst used by these authors, is a base, and no mention is made of the use of halogen containing or acidic catalysts, as used herein.
E. Boyd, et. al., Tet. Lett., vol. 31, p. 2933-2936 (1990), report the reaction of triethylammonium phosphinate, trimethylchlorosilane, and alpha,beta-unsaturated ester (such as an acrylate) resulted in the formation of (beta-ester)alkyl substituted phosphonic acid. Bis(trimethylsilyl)phosphinite was postulated as an intermediate. However, only alpha-beta unsaturated esters are reported to be suitable reactants.
Similarly, J. K. Thottahil, et. al., Tet. Lett., vol. 25, p. 4741-4744 (1984), reports that phosphonous esters in the presence of trimethylchlorosilane, and triethylamine react with substrates suitable for Michael addition type reactions (i.e., alpha, beta unsaturated esters and aldehydes) to give various addition products to the phosphonous ester. Depending on the reactants, 1,2 or 1,4 addition was obtained. N,O-Bis(trimethylsilyl)acetamide could be used in place of trimethylchlorosilane. No mention is made in this paper of using amines, such as a vinylpyridine, as substrates.
M-P. Teulade and P. Savignac, Synthesis-Stutt., vol. 11, p. 1037-1039 (1987) report the reaction of triethyl phosphite with alpha-beta unsaturated aldimines catalyzed by formic acid. No mention is made of using vinylpyridines as reactants.
U.S. Pat. No. 4,912,175 describes the use of 2-(pyridyl)ethyl phosphonic esters and acids as catalysts for increasing the molecular weight of polyamides such as nylon 6,6. No mention is made of the use of silyl esters as such catalysts.
It is the object of this invention to provide a convenient, high yield and economic synthesis of 2-(pyridyl)ethyl substituted phosphonate esters, which are useful catalysts for increasing the molecular weight of polyamides. Another objective is to provide novel 2-(pyridyl)ethyl substituted bis(silyl)phosphonate esters that are also useful as catalysts for increasing the molecular weight of polyamides.